UK Prime Minster Liz Truss will step down after just 45 days in office after her economic programme sent shockwaves through the markets and drew widespread criticism, including from her own party members.

In a statement today, Truss said she recognised she could not deliver the mandate on which she was elected by the Conservative Party, and that she had therefore informed the King of her decision to step down from as party leader, and therefore, Prime Minister.

Speaking outside the Prime Ministerial residence, 10 Downing Street, Truss said she will remain in office for one week while a successor is chosen.

According to Sky News, Rishi Sunak and Penny Mordaunt, two contenders in Britain's previous leadership contest this year, are believed to be in the running to become the nation's next prime minister following Truss's resignation.

The contest to replace Liz Truss as PM and Conservative Party leader should be concluded by October 28, Graham Brady, the chair of the Conservative Party's 1922 Committee said on Thursday.

Her departure after 45 days in office makes her the shortest-serving PM in UK history.

(Reporting by Imogen Lillywhite; editing by Seban Scaria)

imogen.lillywhite@lseg.com